There have existed two dominant theoretical frameworks in adult education-critical thinking and self-directed learning. In recent years, critical thinking has been regarded as providing a rationale for the conceptualization and practice of adult education. However, critical thinking has not been much investigated in relation to adult education in Korea. This study was undertaken to inspire adult educators to increase their knowledge of critical thinking and to stimulate to foster critical thinking in adult education and other educational settings in Korea. This article is designed to review and analyze critical thinking with regard to the following issues: concept and definition of critical thinking; critical thinking dispositions and abilities; critical thinking in adult life; history of critical thinking advocated by the leaders of adult education; conceptual models of critical thinking in adult education; relationship between self-directed learning and critical thinking; role of adult educators in facilitating critical thinking; and an analysis of the debates on ideology, intellectual tradition, and risks of critical thinking. The discussion is intended to contribute to our understanding of implications for critical thinking and to encourage further reflection on adult education and overall educational practice in Korea. Considering the prospective change in Korea relating to globalization, information society and the self-government system, it could be concluded that there is a call for development of critical thinking for adults to gain better sense of control of their lives and to sustain a healthy democracy. Furthermore, critical thinking carries strong implications for developing new educational curriculum at any level to enhance the ability of 'how to think.'